1. Field of the Invention
This invention relates to an automobile headlamp having a reflector supported by an aiming mechanism in a lamp body so that the tilting direction of the reflector can be regulated, and more particularly to an automobile headlamp having a reflector fitted with a light-distribution switching mechanism for alternatively switching between light distribution for a low beam and that for a high beam.
2. Description of the Related Art
In a conventional headlamp of the sort mentioned above, a reflector 2 fitted with a light source bulb 3 is as shown in FIGS. 15 and 16 tiltably supported by an aiming mechanism 4 (including two aiming screws 4a and 4b, two nut members 5a and 5b on the reflector 2 side which are screwed onto the respective screws 4a and 4b, and one ball joint 4c) in a lamp body 1. A direction of optical axis L can thus be regulated by tilting the reflector 2 by pivoting the aiming screws 4a and 4b around a horizontal tilting axis Lx (an axis connecting the nut member 5b and the ball joint 4c) and a vertical tilting axis Ly (an axis connecting the nut member 5a and the ball joint 4c). Reference numeral 8 denotes a front lens which is integrally fitted in the front opening of the lamp body 1.
Moreover, a shade 6 for blocking off part of the light directed to the reflector 2 in order to form a predetermined light-distribution pattern is provided around the bulb 3. The shade 6 is supported by a longitudinally-slidable slider 7a and capable of moving along the optical axis L. When the shade 6 is moved to a solid-line position of FIG. 16, then a part of the reflector 2 is functioning as an effective reflective surface, whereby the light distribution for the low beam is formed, whereas when the shade 6 is moved to an imaginary-line position of FIG. 16, then the remaining part of the reflector 2 is also functioning as an effective reflective surface, whereby the light distribution for the high beam is formed. In other words, the slider 7a caused by a motor 7b to run longitudinally forms a light-distribution switching mechanism 7 for alternatively switching between the light distribution for the low beam and that for the high beam.
Since the light-distribution switching mechanism 7 is provided for the reflector 2 in the aforementioned conventional headlamp, however, a reflector-side load (weight) applied onto the aiming mechanism 4 (including the two aiming screws 4a and 4b, the two nut members 5a and 5b, and the one ball joint 4c) becomes heavy. Consequently, smooth optical axis adjustment becomes difficult because the pivoting torque of the aiming screws 4a and 4b is stronger.
There are also other problems arising from failing to obtain adequate light distribution because the bending of the aiming screws 4a and 4b used for supporting the reflector 2 in a cantilever style causes the reflector 2 to sag, and making light distribution oscillate vertically because the reflector 2 is pivoted in the vertical direction.